Coast FIRE is the point where your invested assets are large enough to grow to your full retirement number on their own — no additional contributions required. Reaching it does not mean you retire today, but it does mean your future retirement is secured. Understanding this milestone and how to reach it faster is one of the most motivating frameworks in the FIRE movement.
What Coast FIRE Actually Means
Coast FIRE is a specific milestone within the broader Financial Independence, Retire Early (FIRE) framework. When you hit your Coast FIRE number, your current investment balance — left alone to compound at your expected real return — will grow to your full FIRE number by the time you reach your planned retirement age. The key phrase is "left alone": you do not need to add another dollar. You have effectively pre-funded your retirement and are just waiting for time and compound interest to complete the job. This is a powerful psychological shift. Before Coast FIRE, every month of not saving feels like falling behind. After Coast FIRE, you have optionality — you can continue saving aggressively to retire earlier, scale back to a less demanding job, switch careers entirely, or work part-time and cover only current expenses. The pressure of needing to save for the future evaporates. Unlike full FIRE, which requires enough saved to stop working immediately, Coast FIRE only requires enough invested today that your future self is financially secure regardless of what happens with your career or income from this point forward.
How the Coast FIRE Calculation Works
The calculation has two steps. First, determine your FIRE number: divide your expected annual retirement spending by the safe withdrawal rate you choose. If you plan to spend $60,000 per year and model a 4% rate, the gross FIRE number is $1,500,000. If other income will cover part of that spending, the calculator subtracts that income before calculating the portfolio-funded Coast FIRE target. Second, discount the portfolio target back to today's dollars using the real rate of return — (1 + nominal return) / (1 + inflation) − 1. For example, a 7% nominal return and 3% inflation produce a 3.88% real return; with 28 years until retirement, $1,500,000 / (1.0388)^28 is approximately $516,000. Every result depends on the assumptions, so compare several return, inflation, spending, and withdrawal-rate scenarios rather than relying on one projection.
The Role of the Safe Withdrawal Rate
Your safe withdrawal rate (SWR) is the percentage of your retirement portfolio you plan to withdraw in the first year. The calculator applies that percentage to the portfolio-funded spending target; lowering the rate increases the required FIRE and Coast FIRE amounts. Historical studies can provide context, but they do not guarantee future results, and a withdrawal plan may need to account for taxes, fees, changing spending, market volatility, and the length of retirement. Compare multiple SWR assumptions and consider professional advice for a personal plan.
Life After Coast FIRE
Reaching Coast FIRE opens doors that are closed when you are still in the accumulation phase. Many people use the milestone to transition from high-paying but stressful careers to work they find more meaningful, even at lower salaries. Since covering current expenses is all that is required — not building future retirement savings — a significant income reduction becomes sustainable. This pattern, sometimes called Barista FIRE or Semi-FIRE, allows people to step off the aggressive savings treadmill while their invested assets continue compounding in the background. Others use Coast FIRE as confirmation to accelerate: knowing the retirement floor is secured, they focus any additional savings on paying off a mortgage, funding a business, or building a taxable brokerage account for early retirement years. The psychological value of knowing your retirement is already locked in — regardless of what happens to your income — is hard to overstate. It changes how you negotiate salary, tolerate a difficult boss, and make career decisions, because your long-term financial security no longer depends on any single employer or income stream.